1. Field of the Invention
The present invention relates to an audio output apparatus and method and, more particularly, relates to an audio output apparatus and method capable of accurately reproducing input audio.
2. Description of the Related Art
Audio output apparatuses for outputting audio by allowing a plate-shaped flat panel (oscillation enhancing panel) to oscillate by means of a transducer are widely known. Such audio output apparatuses can project sound over a wider area than cone-shaped audio output apparatuses and thus have advantages that the sweet spot (optimum listening area) thereof is wide.
In order to more accurately reproduce input audio, there has been a demand for an audio output apparatus to have frequency characteristics as flat as possible. That is, when an audio signal of audio whose sound volume (audio level) has the same constant value for every frequency is input to an audio output apparatus and is reproduced, the closer to a constant state the sound volume (audio level) for every frequency of audio reproduced by the audio output apparatus, the more accurately the audio output apparatus can reproduce the input audio.
In an audio output apparatus of the related art, in order to realize frequency characteristics as flat as possible, the position of a transducer in an oscillation enhancing panel is changed on the basis of results of the analysis of parameters of the power transmission of the oscillation enhancing panel (refer to, for example, PCT Japanese Translation Patent Publication No. 2003-522426).
Furthermore, there is a known apparatus in which, in order to reduce feature points that occur at a coincidence frequency, two transducers arranged in an oscillation enhancing panel are separated by a distance of a half wavelength of the coincidence frequency of the oscillation enhancing panel (refer to, for example, PCT Japanese Translation Patent Publication No. 2002-532038). Also, there is a known apparatus in which a small oscillation enhancing panel and a large oscillation enhancing panel larger than the small oscillation enhancing panel are made to overlap each other, and audio of a wide frequency bandwidth is reproduced by driving these oscillation enhancing panels by using the same exciter (refer to, for example, PCT Japanese Translation Patent Publication No. 2002-505814).